Micrograft for the treatment of intracranial aneurysms and method for use

ABSTRACT

A device for occluding a vasculature of a patient including a micrograft having an absorbent polymeric structure with a lumen of transporting blood. The micrograft has a series of peaks and valleys formed by crimping. The occluding device is sufficiently small and flexible to be tracked on a guidewire and/or pushed through a microcatheter to a site within the vasculature of the patient. Delivery systems for delivering the micrografts are also disclosed.

This application is a continuation of application Ser. No. 14/997,008,filed Jan. 15, 2016, which claims priority from provisional application62/105,648, filed Jan. 20, 2015. The entire contents of each of theseapplications are incorporated herein by reference.

BACKGROUND Technical Field

This application relates to medical devices, and more particularly, tovaso-occlusive devices used in the treatment of intracranial aneurysms.

Background of Related Art

An aneurysm is a localized, blood filled balloon-like bulge that canoccur in the wall of any blood vessel, as well as within the heart. Oneendovascular treatment option for aneurysms is complete reconstructionof the damaged vessel using a vascular prosthesis or stent-graft. Astent-graft is an implantable tubular structure composed of two parts, astent and a graft. The stent is a mesh-like structure made of metal oralloy which functions as a scaffold to support the graft. The graft istypically a synthetic fabric that is impervious to blood flow and linesthe stent. Stent-grafts are not a treatment option for intracranialaneurysms due to the risk of cutting off blood flow to feeder vesselsthat may be vital for brain function. Stent-grafts can also be stiff,hard to deliver/retract, and can be highly thrombogenic within theparent vessel, all of which are undesirable features for intracranialaneurysm treatment. As a result, endovascular treatment of intracranialaneurysms has centered on packing or filling an aneurysm with materialor devices in order to achieve a high packing density to eliminatecirculation of blood, which leads to thrombus formation and aneurysmclosure over time.

There have been a variety of materials and devices described for fillingthe sac of an intracranial aneurysm such as injectable fluids,microfibrillar collagen, polymeric foams and beads. Polymeric resinssuch as cyanoacrylate have also been used. Both are typically mixed witha radiopaque resin to aid in visualization. These materials pose asignificant risk due to the difficulty of controlling dispersion and inretrieving them, if improperly or excessively delivered.

Mechanical vaso-occlusive devices are another option for filling ananeurysm. One type of mechanical vaso-occlusive device for the placementin the sac of the aneurysm is a balloon. Balloons are carried to thevessel site at the end of a catheter and inflated with a suitable fluid,such as a polymerizable resin, and released from the catheter. The mainadvantage of the balloon is its ability to effectively fill the aneurysmsac. However, a balloon is difficult to retrieve, cannot be visualizedunless filled with contrast, has the possibility of rupture, and doesnot conform to varying aneurysm shapes.

Other types of mechanical vaso-occlusive devices are composed of metalsor alloys, and biocompatible fibers, for example. Generally, thematerials are formed into tubular structures such as helical coils. Oneof the earliest fibered coils was the Gianturco coil (Cook Medical).This coil was formed from a 5 cm length of 0.036″ guidewire (inner coreremoved) and featured four 2 inch strands of wool attached to one tip ofthe coil to promote thrombosis. This device was difficult to introduceinto tortuous vessel sites less than 3 mm in diameter. This is generallybecause the coil was stiff or bulky and had a high coefficient offriction.

Chee et al. (U.S. Pat. No. 5,226,911) introduced a more deliverablefibered coil with fibers that were directly attached to the length ofthe coil body. This coil was designed for more tortuous anatomy bydecreasing the amount of thrombogenic material being delivered with thecoil. Other examples of coils are U.S. Pat. No. 4,994,069 to Ritchart etal.; U.S. Pat. No. 5,354,295 and its parent, U.S. Pat. No. 5,122,136,both to Guglielmi et al.

Materials can also be formed into tubes/strings/braided sutures (see,e.g., U.S. Pat. No. 6,312,421 to Boock; U.S. patent application Ser. No.11/229,044 to Sepetka et al.; U.S. patent application Ser. No.13/887,777 to Rees; U.S. patent application Ser. Nos. 13/552,616 and10/593,023 both to Wu et al.), cables (see, e.g., U.S. Pat. No.6,306,153 to Kurz et al.), or braids. Metal coils can also be covered bywinding on thrombogenic fiber as described in U.S. patent applicationSer. No. 12/673,770 to Freudenthal and U.S. Pat. No. 6,280,457 toWallace et al.

Unlike other tubular structures, braided or polymer coils can be furtherdivided into non-expandable and self-expandable devices. These devicescan be made from materials such as textiles, polymers, metal orcomposites using known weaving, knitting, and braiding techniques andequipment. Included in the weave or the finished braid can be optionalmono or multifilament fiber manufactured to impart additional featuresor effects (e.g., radiopacity and thrombogenicity).

Non-expandable braids (see, e.g. U.S. Pat. No. 5,690,666 to Berensteinet al.; U.S. Pat. No. 5,423,849 to Engelson et al.; and U.S. Pat. No.5,964,797 to Ho) can act as the implant and be mainly metallic, polymer,or a combination of metal and polymer. In such designs, braids have someminimal space between the filaments (braid strands) resulting in opencell designs. In addition, tight, mostly metal braids employing suchdesigns result in stiff structures which are difficult to track viacatheter or risk injury to the vasculature. Also, metal braidedstructures may be rough to the touch if not covered or furtherprocessed.

These braids can be formed into secondary shapes, such as coils thathave little or no inherent secondary shape, they can be dimensioned toengage the walls of the aneurysm, or they can have other shapes (e.g.random, “flower”, or three dimensional). These structures can also havea fiber bundle(s) in, or protruding from, the interior core made ofnatural fibers or thermoplastics infused with drugs to help withclotting (see, e.g., U.S. Pat. No. 5,423,849 to Engelson et al.; andU.S. Pat. No. 5,645,558 to Horton). Coiled braids can also be suppliedwith bio-active or other surface coatings (see, e.g., U.S. Pat. No.6,299,627 to Eder et al.).

Non-expandable braids can also cover core or primary structures, such ascoils or other braids (see, e.g., U.S. Pat. No. 5,382,259 to Phelps etal.; U.S. Pat. No. 5,690,666 to Berenstein et al.; U.S. Pat. No.5,935,145 to Villar et al.; and U.S. Pat. No. 8,002,789 to Ramzipoor etal.). Much like the above braid structures, these covers have open celldesigns (e.g., inner coil structure is visible through the braid).

Regardless of configuration, it is difficult to achieve high packingdensities and rapid flow stagnation with these devices as they have opencell construction which allows at least some blood flow through thewall, may not compress adequately, and/or may have limited bend radii.If an aneurysm sac is not sufficiently packed to stop or slow bloodflow, any flow through the neck of the aneurysm may prevent stasis orcause coil compaction, leading to recanalization of the aneurysm.Conversely, tight packing of metal coils in large or giant aneurysms maycause increased mass effect (compression of nearby tissue and stretchingof aneurysm sac) on adjacent brain parenchyma and cranial nerves. Coilprolapse or migration into parent vessels is another possible issue withnon-expanding devices, especially in wide neck aneurysms.

Braids may also be self-expanding and can be shaped into various formssuch as a ball, a coil(s), and a combination braid-stent. Examples ofself-expanding devices are disclosed in the following: U.S. Pat. No.8,142,456 to Rosqueta et al.; U.S. Pat. No. 8,361,138 to Adams; U.S.patent application Ser. No. 13/727,029 to Aboytes et al.; U.S. patentapplication Ser. No. 14/289,567 to Wallace et al.; U.S. patentapplication Ser. No. 13/771,632 to Marchand et al.; and U.S. patentapplication Ser. No. 11/148,601 to Greenhalgh.

Self-expanding braids are expected to occupy all or substantially all ofthe volume of an aneurysm to obstruct flow and/or promoteendothelization at the neck. A major problem for these designs issizing. The implant has to be accurately sized so that upon expansion itoccupies enough volume to fill the entire aneurysm, dome to neck.Undersized devices lead to insufficient packing as described above,whereas oversizing risks rupturing the aneurysm or blockage of parentvessel.

Neck bridges are yet another approach to treating intracranialaneurysms. They can be broken down into two categories: those that actas support to keep the coil mass from migrating into a parent vessel(coil retainer) and those that span the neck to obstruct flow into theaneurysm. Neck bridges that support the coil mass tend to bepetal/flower shaped and span the neck of the aneurysm or placed betweenthe parent vessel and aneurysm sac. Examples of neck bridges forsupporting the coil mass are disclosed in the following: U.S. Pat. No.6,193,708 to Ken et al.; U.S. Pat. No. 5,935,148 to Villar et al.; U.S.Pat. No. 7,410,482 to Murphy et al.; U.S. Pat. No. 6,063,070 to Eder;U.S. patent application Ser. No. 10/990,163 to Teoh; and U.S. Pat. No.6,802,851 to Jones et al.

Neck bridges that obstruct flow through the aneurysm neck can bedeployed either internal or external to the aneurysm and may not requiredeployment of embolization coils. Examples of intra-aneurysmal neckbridges with deployment at the base of the aneurysm sac with componentsextending into the neck are disclosed in U.S. Pat. No. 6,454,780 toWallace; U.S. Pat. No. 7,083,632 to Avellanet et al.; U.S. Pat. No.8,292,914 to Morsi; and U.S. Pat. No. 8,545,530 to Eskridge et al.Examples of neck bridges deployed external to the aneurysm (in theparent vessel) are disclosed in U.S. Pat. No. 6,309,367 to Boock; U.S.Pat. No. 7,241,301 to Thramann et al.; and U.S. Pat. No. 7,232,461 toRamer; U.S. Pat. No. 7,572,288 to Cox; U.S. patent application Ser. No.11/366,082 to Hines; U.S. patent application Ser. No. 14/044,349 to Coxet al.; U.S. Pat. No. 8,715,312 to Burke; U.S. Pat. No. 8,425,548 toConnor; and U.S. Pat. No. 8,470,013 to Duggal et al. Neck bridges canalso have surface treatment to encourage neointima formation asdisclosed in U.S. Pat. No. 6,626,928 to Raymond et al. Regardless ofdesign, neck bridges pose several problems when treating intracranialaneurysms. The first major challenge is deployment of these devices,which requires the bridge to be maneuvered and often re-positioned overthe aneurysm neck to assure complete coverage. Secondly, ifrecanalization occurs, any subsequent retreatment of the aneurysm willbe hampered due to access being restricted by the neck bridge or one ofits components.

Stents and flow diverters are similar to neck bridges in function, butare intended for parent vessel reconstruction and therefore run distalto proximal of the aneurysm, covering the neck. Such devices aredeployed in the parent vessel and are intended to act as a physicalblood flow barrier to induce sac embolization, stabilize embolic coils,and prevent coil protrusion and/or migration. Flow diverters, due totheir relative low porosity (high coverage), can be used with or withoutcoils and have been found to promote thrombus formation by restrictingblood flow into the aneurysm sac. However, complications such asrecanalization, delayed stent thrombosis, delayed aneurysm rupture, andstent migration have also been observed. An example of a stent isdisclosed in U.S. Pat. No. 6,746,475 to Rivelli and a flow diverter isdisclosed in U.S. Pat. No. 8,398,701 to Berez et al.

While the above methods attempt to treat intracranial aneurysms withminimally invasive techniques, there remains a need for a highlycompliant and thrombogenic filler that blocks blood flow within the sacof the aneurysm without the drawbacks of current devices. For example,it would be advantageous to provide a device that achieves sufficientflexibility to enable advancement through the tortuous vasculature intothe cerebral vasculature and achieves high packing densities whilemaintaining a high concentration of thrombogenic material. It would alsobe advantageous to provide such device which is simple in structure andsimple to manufacture without sacrificing efficacy. Still further, sincethe device is designed for minimally invasive insertion, such deviceneeds to be easy to deliver and deploy at the intracranial site as wellas manufacturable in a small enough size for use in cerebralvasculature. All of this needs to be achieved with a construction thateffectively packs the aneurysm without damaging the sac or other tissuewhile promoting rapid clotting and healing of an intracranial aneurysmwith reduction in mass effect. To date, no device effectively achievesall these objectives, with current devices at best achieving oneobjective at the expense of the other.

SUMMARY OF INVENTION

The present invention provides an intra-aneurysmal micrograft thatovercomes the above discussed limitations and deficiencies in treatinganeurysms, especially intracranial aneurysms. The present invention alsoprovides intra-aneurysmal micrograft delivery systems for deliveringmicrografts to an intracranial aneurysm.

In accordance with one aspect, the present invention provides a vasculargraft configured for occluding a vasculature of a patient comprising:

-   -   an absorbent biocompatible structure; and    -   a core element having a proximal end, a distal end and a lumen        within the core element, the core element positioned inside the        biocompatible structure and attached to the biocompatible        structure;    -   wherein a capillary effect is created within the vascular graft        when the biocompatible structure is exposed to blood such that        blood is transported in a proximal direction through the        vascular graft wherein blood clots.    -   In some embodiments, a lumen in the core element is dimensioned        to transport blood in a proximal direction.

In some embodiments, the vascular graft is non-self-expanding. In someembodiments, the core element has a coiled structure and the graftfurther comprises a tube positioned within coils of the coiledstructure. In some embodiments the vascular graft has an outer diameterless than 0.027 inches.

In some embodiments, the biocompatible structure is a textile structurewhich includes a plurality of yarns spaced to wick blood when placed incontact with blood. The plurality of yarns can each be formed by aplurality of fibers, the fibers spaced to wick blood when placed incontact with blood.

In some embodiments, the polymeric structure is crimped to form a seriesof peaks and valleys along a surface of a wall to increase flexibility

The vascular graft can include a radiopaque element within the vasculargraft. The vascular graft in some embodiments is shape set to anon-linear configuration wherein it is movable to a substantially linearconfiguration for delivery and returns to the same or differentnon-linear configuration for placement within the vasculature.

In some embodiments, the core element is made of a radiopaque material.In some embodiments, the core element is wound into an open pitchhelical coil.

In accordance with another aspect of the present invention, an occludingdevice for treating an intracranial aneurysm of a patient is providedcomprising an elongate tubular structure having a plurality of yarns anda longitudinal axis extending in a distal to proximal direction. Thetubular structure is crimped to alter the shape of the yarns and providea first series of peaks defined by the yarns and a first series ofvalleys formed between the yarns and a second series of peaks and secondseries of valleys formed in the tubular structure in a longitudinaldirection to increase the flexibility of the tubular structure.

In some embodiments, each of the plurality of yarns is formed by aplurality of polymer filaments, the plurality of filaments having afirst set of pores (capillary spaces) therebetween for absorption ofblood to create a first capillary effect and the plurality of yarnshaving a second set of pores (capillary spaces) therebetween forabsorption of blood to create a second capillary effect. In someembodiments, the plurality of yarns and plurality of filaments wickblood and the occluding device further has a lumen therein through whichblood can flow into to create a third capillary effect. The lumen caninclude a distal opening for blood. In some embodiments, the occludingdevice is shape set to a non-linear configuration.

In accordance with another aspect of the present invention, a system foroccluding a vasculature of a patient is provided comprising a vascularmicrograft having an absorbent polymeric structure, a lumen for passageof blood therein, an outer wall, and a retaining structure attached tothe vascular micrograft. A delivery element has an engagement structurecooperating with the retaining structure to retain the vascularmicrograft during insertion by the delivery element through thevasculature.

In some embodiments, the micrograft is positioned coaxially on thedelivery element.

In some embodiments, the retaining structure includes a radiopaquemarker band positioned within an internal portion of the vascularmicrograft and the engagement structure includes a taper on the deliveryelement for frictionally engaging a proximal portion of the vascularmicrograft. In other embodiments, the engagement structure includes aplurality of members movable from a first expanded position to a secondgrasping position to grasp the retaining structure. In some embodiments,the retaining structure includes a tab movable between a first engagedposition and a second non-engaged position.

The system can further include a pusher catheter (member), the deliveryelement extending through the pusher catheter, and the micrograft havinga diameter less than 0.027″ for delivery through a microcatheter to anintracranial aneurysm.

In accordance with another aspect of the present invention, a system fortreating an aneurysm in a vessel of a patient is provided comprising:

-   -   an implantable occluding device configured for introduction into        a lumen of the vessel, the occluding device having a first lumen        for passage of blood therein;    -   a delivery member, the occluding device mounted on the delivery        member such that a portion of the delivery member extends into        the first lumen of the occluding device; and    -   a catheter having a second lumen, the delivery member extending        through the second lumen;    -   wherein proximal movement of the delivery member exposes the        first lumen for passage of blood therethrough in a capillary        action as blood displaces the delivery member as the delivery        member is withdrawn proximally from the first lumen.

In some embodiments, the delivery member extends distally beyond theoccluding device during delivery of the occluding device to theaneurysm. In some embodiments, the occluding device has a porous outerwall.

In some embodiments, a clearance between an outer dimension of thedelivery member and an inner dimension of the occluding device issubstantially fluid-tight before delivery into the aneurysm butsufficient to enable slidable movement of the delivery member withrespect to the occluding device.

In some embodiments, the delivery member is configured for deliverythrough a catheter having a diameter less than or equal to 0.027″.

In some embodiments, the catheter has a distal portion in abutment withthe occluding device to advance the occluding device off the deliverymember into the aneurysm.

In some embodiments, the occluding device is a polymer structure formedas a non-expanding braid composed of multiple multi-filament yarns ofpolymeric material. In some embodiments, the polymer structure isabsorbent and wicks blood via a capillary action in a distal to proximaldirection.

In some embodiments, the occluding device includes retaining structureengageable with an engagement structure of the delivery member to retainthe occluding device on the delivery member.

In some embodiments, the occluding device is shape set to a non-linearconfiguration and advanceable from a substantially linear configurationcoaxially positioned on the delivery member to the same or differentnon-linear configuration placed within the aneurysm.

In accordance with another aspect of the present invention, a method fortreating an intracranial aneurysm is provided comprising the steps of:

a) providing an occluding device having a lumen therein;

b) providing a delivery member;

c) inserting the delivery member with the occluding device into theaneurysm, the delivery member retaining the occluding device duringdelivery of the occluding device to the aneurysm;

d) retracting the delivery member proximally within the lumen of theoccluding device to provide a gap for blood flow in the lumen of theoccluding device; and

e) subsequently moving a pusher member to advance the occluding deviceoff the delivery member.

Preferably, the delivery member is inserted into a microcatheter fordelivery to the aneurysm.

In some embodiments, the occluding device is assembled of fibers forminga fibrous structure.

In some embodiments, the delivery member is inserted into the pushermember prior to advancing the delivery member through a microcatheter tothe aneurysm.

In some embodiments, the step of retracting the delivery member includesretracting the delivery member until it is aligned with a marker bandattached to the occluding device.

In some embodiments, the occluding device is preset to a non-linearconfiguration and advancement of the occluding device into the aneurysmreturns the occluding device from a substantially linear configurationcoaxially positioned on the delivery member for delivery to the same ordifferent non-linear configuration placed within the aneurysm.

In some embodiments, the delivery member is a wire having a curved orshaped tip.

In some embodiments, the step of inserting the delivery member includesthe step of passing the delivery member through a catheter positioned ina stent in the vasculature. In some embodiments, the occluding devicecan be guided within the aneurysm by the delivery member.

In accordance with another aspect of the present disclosure, a methodfor manufacturing a vaso-occlusive device is provided comprising thesteps of:

-   -   a) braiding a series of multifilament yarns over a mandrel to        create a braid having an elongate body of coaxially aligned        filaments having a proximal portion, a distal portion, and a        lumen extending therebetween along a longitudinal axis;    -   b) compressing the elongated body longitudinally over the        mandrel until the elongate body buckles creating a sinusoidal        shape having a series of peaks and valleys along a length of the        body and bundles of individual filaments of the multifilaments        within the yarns orient substantially transversely to a        longitudinal axis of the mandrel to create a series of smaller        peaks and valleys along the length of the body;    -   c) after step (b) heat setting the braid to set the peaks and        valleys; and    -   d) removing the braid from the oven.

In some embodiments, an internal stop extends from the body of thedevice for cooperation with a delivery member. In some embodiments, thestep of braiding leaves pores between the series of multifilament yarns.

The present invention also provides in some aspects methods for fillingand infusing an intra-aneurysmal micrograft with blood or another liquidand delivering it to an intracranial aneurysm.

The present invention also provides in some aspects a system forviscosity based retraction of intra-aneurysmal micrografts back inside acatheter.

In one aspect, an intra-aneurysmal micrograft is provided having atubular body that has a textile construction with a through lumen thathas a series of peaks and valleys, or a wavy profile (dependent on wallthickness), running longitudinally across its length. At either end ofthe tubular body, bands can be provided which may optionally beradiopaque and/or used for mating to a delivery system. In another formof the construction, one or both ends of the graft can be shape set witha “J” or curl or other shape that help with delivery. In yet anotherform of the construction, agents can be added to the inner or outerdiameter of the tubular body to aid in delivery (visualization), cancertreatment and/or endothelial cell growth.

In some embodiments, the micrograft has a variable stiffness tubularstructure that has been shape set to have secondary shapes such as ahelical coil. The change in stiffness may be indicated by a radiopaquemarker band or reduced/compressed section. In some embodiments, a singleend or both ends of the micrograft can be frayed to create Velcro-likelocks that mate with other micrografts sharing the same feature.

In some embodiments, the micrograft structure is formed to be directableby blood flow. The micrograft may be cut longitudinally and shape set toexpose an inner surface or it may be a tubular form. Additionally, themicrograft may have holes or slots.

In any of the foregoing, the micrograft can be formed using a braidedmulti-filament polyester (e.g., PET) yarn, but it may be formed of otherflexible mono or multi-filament fibers, yarns, or textile materials.

In one embodiment of a delivery system, a delivery wire with one or morepre-mounted micrografts is inserted into an over-the-wire pushercatheter having a through lumen. In some embodiments, the delivery wireis a guidewire pre-mounted with one or more micrografts. In yet anotherembodiment, the micrograft is loaded on the primary guidewire usedduring a procedure. In some embodiments, the pusher catheter is a rapidexchange catheter.

In one embodiment of the delivery system, a pusher wire with grasperarms with bands engages a band, or thickened section, on a proximal endof the micrograft inside a delivery tube.

In another embodiment of the delivery system, a push wire engages astent or flow diverter device which in turn engages a micrograft insidea delivery tube.

In another alternate embodiment of a delivery system, a micrograft isloaded into an introducer tube and used in combination with a pushercatheter (member).

In accordance with one aspect of the present invention, a method ofplacing and deploying a micrograft is as follows. A pre-loaded deliverywire with a micrograft is loaded into a pusher catheter (proximal end ofwire loaded into distal end of pusher catheter) until the distal end ofthe pusher contacts the micrograft. This system is then advanced to ananeurysm through a microcatheter that has been previously placed at theintended anatomical site. Once the delivery wire and distal end of themicrograft reach the tip of the microcatheter, the delivery wire tip ispulled back inside the micrograft just distal of the lock. As the wireis drawn back, blood fills the volume displaced by the wire inside themicrograft. Once filled with blood, the delivery system is advanceduntil the micrograft is deployed. When placed in the desired position,the micrograft is detached by retracting delivery wire tip, or furtheradvancing pusher catheter, until the tip of the wire pulls through thelock and into the pusher. In this method, as long as the wire tipremains distal to the micrograft lock, the micrograft can be retrieved.Once the micrograft is deployed, the delivery system is removed and, ifnecessary, another pre-loaded delivery wire is selected and the processfor delivering a micrograft is repeated until the aneurysm issufficiently packed with micrografts.

In an alternate method, multiple micrografts are loaded onto a singledelivery wire. In some embodiments, instead of the delivery wire, astandard guidewire is loaded with a micrograft of the present inventionduring the procedure and the guidewire with loaded micrograft can beused as a primary access wire. The pusher catheter in an alternateembodiment is a rapid exchange catheter.

In some embodiments of the delivery method, the micrograft is directedfor placement within the aneurysm using either a shaped delivery wire orthe microcatheter tip.

In some embodiments a micrograft is directed by blood flow once releasedfrom the microcatheter.

In some embodiments of the delivery method, the proximal end of themicrograft is locked by a series of arms extending distally from a pushwire that are compressed by advancing a loading tube. In such method, todeliver the micrograft, the distal end of the loading tube is insertedinto a microcatheter luer and locked in place with the RotatingHemostatic Valve (RHV). The push wire with micrograft is then advancedthrough the microcatheter until it reaches the distal tip of thecatheter. The micrograft is deployed by pushing the arms of pusher wireout of the microcatheter so they can expand and release the micrograft.The pusher arms can then be used to move the micrograft around in theaneurysm or to grasp and retrieve it. Like the previous method, thisprocess can be repeated to insert additional micrografts until theaneurysm is densely packed.

In some embodiments of the delivery method, the micrograft is deliveredin tandem with a stent or flow diverter through a microcatheter.

In some embodiments, a micrograft is pushed through a microcatheter intoan aneurysm without a delivery wire.

These and other features of the invention will become more fullyapparent when the following detailed description is read in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view partial cut away of an intra-aneurysmal micrograftin accordance with one embodiment of the present invention;

FIG. 2A is a view of another embodiment of the intra-aneurysmalmicrograft of the present invention having a larger diameter and thinnerwall;

FIG. 2B is a side view similar to FIG. 2A except showing the micrograftstretched to highlight the peaks and valleys;

FIG. 2C is a side view of the micrograft of FIG. 2A in a bent placementposition;

FIG. 3A is a side view of another embodiment of the intra-aneurysmalmicrograft formed into a helical shape;

FIG. 3B is a side view of another embodiment of the intra-aneurysmalmicrograft having a flared end to be directed by blood flow;

FIG. 4A is a side view partial cut away of an intra-aneurysmalmicrograft in accordance with another embodiment of the presentinvention;

FIG. 4B is an enlarged view of one end of the micrograft of FIG. 4A;

FIG. 4C is side view of one end of an alternate embodiment of themicrograft of the present invention;

FIG. 4D is a cross-sectional side view of the micrograft of FIG. 4Aplaced over a mandrel before crimping;

FIG. 4E is a cross-sectional side view of the micrograft of FIG. 4Dafter crimping;

FIG. 5A is a side view of an intra-aneurysmal micrograft delivery systemin accordance with an embodiment of the present invention;

FIG. 5B is a side view of the delivery wire and mounted micrograft ofFIG. 5A;

FIG. 5C is an enlarged partial cross-sectional view of theintra-aneurysmal micrograft of FIG. 5B showing the mating of themicrograft with the taper of the delivery wire;

FIG. 5D is a side view of the pusher catheter of FIG. 5A without thedelivery wire;

FIG. 5E is a side view of an alternate embodiment of the micrograftdelivery system of the present invention;

FIG. 5F is an enlarged cross-sectional view of a portion of the deliverysystem of FIG. 5E shown in the locked position;

FIG. 5G is view similar to FIG. 5F showing the delivery system in theunlocked position;

FIG. 5H is a view similar to FIG. 5G showing the delivery systemwithdrawn and the micrograft fully deployed;

FIG. 6 is a side view of a rapid exchange pusher catheter for micrograftdelivery in accordance with another embodiment of the present invention;

FIG. 7 is a side view of another embodiment of the intra-aneurysmalmicrograft delivery system of the present invention having a pusher wirewith locking arms;

FIG. 8 is a side view of another embodiment of the intra-aneurysmalmicrograft delivery system of the present invention using a stent orflow diverter to push the micrograft;

FIG. 9 is a side view of an intra-aneurysmal micrograft introducersystem in accordance with another embodiment of the present invention;

FIG. 10 is a side view illustrating the loading of an intra-aneurysmalmicrograft delivery system of FIG. 5A into a microcatheter;

FIGS. 11A-11F illustrate delivery of an intra-aneurysmal micrograft intoan intracranial aneurysm in accordance with an embodiment of the presentinvention wherein:

FIG. 11A shows the delivery wire inserted into the aneurysm sac;

FIG. 11B shows initial advancement of the micrograft into theintracranial aneurysm after removal of the wire;

FIG. 11C is an enlarged cross-sectional view of the micrograft exitingfrom the catheter corresponding to the position of FIG. 11B;

FIG. 11D shows the micrograft fully deployed from the catheter andpositioned in the intracranial aneurysm;

FIG. 11E is an enlarged cross-sectional view of the deployedblood-filled micrograft corresponding to the position of FIG. 11D;

FIG. 11F shows multiple micrografts of FIG. 11E positioned in theintracranial aneurysm sac;

FIGS. 12A-12C illustrates directed delivery by the delivery wire of anintra-aneurysmal micrograft into an aneurysm in accordance with anembodiment of the present invention;

FIG. 13 illustrates delivery of smaller length flow directedintra-aneurysmal micrografts into an intracranial aneurysm in accordancewith another embodiment of the present invention;

FIG. 14 illustrates delivery of the delivery wire carrying theintra-aneurysmal micrograft through cells of a stent or flow diverterinto an aneurysm in accordance with another delivery method of thepresent invention;

FIG. 15 illustrates delivery of an intra-aneurysmal micrograft into ananeurysm using a delivery wire with the arms of FIG. 7;

FIG. 16A is a photograph of an uncrimped tubular PET braid alongside acrimped braid of the present invention to show a wave-like profile as inFIG. 1A;

FIG. 16B is a photograph of a crimped micrograft braid alongside acrimped micrograft braid that has been heat set into a coiled shape inaccordance with an embodiment of the present invention;

FIG. 16C illustrates a micrograft tubular body of the present inventionpartially filled with a fluid to illustrate the capillary effect.

FIG. 17 is a photograph of one end portion of the micrograft of FIG. 1A;

FIGS. 18A and 18B are flowcharts summarizing alternate methods ofplacing and deploying a micrograft of the present invention; and

FIG. 19 is a flowchart summarizing viscosity lock function in accordancewith an embodiment of the present invention.

DETAILED DESCRIPTION

The following embodiments are described in sufficient detail to enablethose skilled in the art to practice the invention, and it is understoodthat structural changes may be made without departing from the scope ofthe present invention. Therefore, the following detailed description isnot to be taken in a limiting sense. Where possible, the same referencenumbers are used throughout the drawings to refer to the same or likecomponents or features.

FIG. 1 illustrates a partial cut away side view of an intra-aneurysmalmicrograft for insertion into an intracranial aneurysm in accordancewith one embodiment of the present invention. The micrograft of thisembodiment, designated generally by reference number 10, includes abiocompatible non-self-expandable absorbent braided polymeric textiletubular body 12 that has been crimped to reduce stiffness and increasewall thickness and fabric density. The micrograft 10 has sufficientstiffness as well as sufficient flexibility to provide the advantagesdescribed below. It further is structured to enable a triple capillaryaction to promote blood clotting as also discussed in detail below. Themicrograft further preferably has a high surface area for increasedblood absorption, is radially deformable, has a low friction surface forease of delivery and can be shape set to enhance packing of theaneurysm. These features and their advantages are described in moredetail below. Note the micrografts of the present invention areespecially designed to induce blood stagnation or clot to rapidly treatthe aneurysm. The micrografts are configured for delivery to anintracranial aneurysm, although they can be utilized for occlusion inother aneurysms in other areas of the body as well as for occlusion inother vascular regions or in non-vascular regions.

An over the wire delivery system is provided to deliver the micrograftof the present invention to the aneurysm. Variations of these deliverysystems of the present invention are discussed in detail below.Preferably, multiple micrografts are delivered so that the aneurysm sacis densely packed.

Turning first to the biocompatible micrografts of the present invention(the delivery systems are subsequently discussed) the preferred tubularbody 12 of micrograft 10 is constructed of substantially 100% 20denier/18 filament polyester (e.g., PET) multi-filament interlacedyarns, but can be made of other combinations of denier and filament suchas 10 denier/16 filament yarn, or 15 denier/16 filament yarn, forexample. That is, each yarn is composed of a plurality of polyesterfilaments having pores or spaces therebetween, and the plurality ofyarns also have pores or spaces therebetween, for reasons describedbelow. The tubular body has a proximal end 14 and a distal end 16, withproximal defined as closer to the user and distal defined as furtherfrom the user such that the distal end is inserted first into theaneurysm. Blood then flows through the micrograft 10 in a distal toproximal direction. The tubular body 12 has a preferred inner diameterin the range of about 0.001 inches to about 0.068 inches, and morenarrowly in the range of about 0.006 inches and about 0.040 inches, forexample about 0.008 inches. It has a length ranging from about 2 mm upto about 150 cm and a preferred outer diameter in the range of about0.002 inches to about 0.069 inches, more narrowly in the range of about0.010 inches to about 0.041 inches, for example about 0.010 to about0.020 inches. Note that although these ranges and dimensions are thepreferred ranges and dimensions, other ranges and dimensions are alsocontemplated. These dimensions provide a sufficiently small sizemicrograft so that the micrograft can be navigated to and into thecranial vasculature for placement within a cranial vessel.

Each of the multi-filament yarns are made of multiple wettablemicro-filaments, or fibers, assembled with spaces (pores) between them,referred to as inter-fiber spaces or pores. The pores are sufficientlysized to induce capillary action when contacted by a liquid, resultingin the spontaneous flow of the liquid along the porous yarn (i.e.,wicking). This capillarity between fibers (intra-fiber) within the yarnis termed as “micro-capillary” action. As a result, a sufficientlywettable and porous yarn will have high wickability and transport liquidalong its length. The multiple filaments also provide a high surfacearea and can be hydrophilic or hydrophobic.

This assembly of the two or more wickable multi-filament yarns into apermeable structure (such as a textile) results in a “macro-capillary”action, i.e., the transporting of liquid between the yarns andthroughout the structure. Such yarns and/or fibers can be textured,flat, twisted, wettable, non-wettable, with beads, of variouscross-sections (tri-lobal, multi-lobal, hollow-round, etc.), coated orhaving a modified surface, composite, reticulated, porous, pre-shrunk,crimped or modified using similar heat treatment or chemical processes.

The multi-filament yarns can be assembled into a textile tubularstructure using a braider or other textile manufacturing equipment andmethods. In general, the braider can be set-up with a program or recipe,spools of multi-filament yarn and an optional core mandrel to braidover. Anywhere from about 8 to about 288 strands of multi-filament yarnmay be used to form the tube, depending on the desired final structuralproperties such as density, picks per inch (PPI), porosity, compliance,etc. If desired, multiple braiders or a braider in combination with acoil winder can be run simultaneously to form a braid over braid orbraid over coil design.

The micrograft 10 is braided over the core mandrel which sets theinternal diameter (ID) of the braid. The core mandrel can be made of avariety of materials such as metal, wire, polymers or other textilefibers. It can also be formed of a stretchable material to aid inremoval during manufacturing.

The micrograft 10 can also include a permanent core element such asshown in the embodiment of FIG. 4A discussed below. The core element canbe made of a variety of materials, and can itself be formed of one ormore filaments, and may optionally be coated. In one embodiment, thecore element is formed of a metal coil having a lumen therein. It can becomposed of platinum-iridium or other materials. The braid and coil canbe heat set at a temperature that would not damage or disintegrate thebraid.

The braiding process may be adjusted for the highest PPI possible so asto produce a tightly interlaced, dense braid without tenting (braidingover itself or overlapping). However, in some cases tenting may bedesirable to produce a useable feature such as a braid bulge or ring forlocking or wall thickening. The braid, while still mounted on the coremandrel, may be heat treated after manufacturing to set the braidstructure, including PPI, and to relieve filament stresses producedduring braiding.

The preferred PPI for the as-braided therapeutic structure, for example,may range from about 80 to about 200 PPI for a 16 strand braid, and morenarrowly in the range of about 120 to about 180 PPI, preferably about167 PPI. The PPI is dependent on the number of strands used to braid,the braid angle, and the braid diameter, such that a braided tube of agiven diameter with 120 PPI and 16 strands would have a PPI of 60 whenbraided using 8 strands at the same diameter (assuming all of thevariables constant). The preferred PPI should be high enough to producea dense interlacing pattern, but not so high as to interfere with coremandrel removal, unless the core is stretchable. Crimping, which will bediscussed later in detail, may be used to increase PPI (and braidangle), once again depending on final structural requirements.

The use of multi-filament yarns in combination with a relatively highPPI of the present invention results in a somewhat stiff, relativelysmall or closed cell (high pick density) braided tube. As mentionedabove, there is a micro-capillary effect resulting in wicking of liquidalong the porous yarns due to inter-fiber spaces and a macro-capillaryeffect resulting in liquid flow between yarns and throughout the textilewall due to inter-yarn porosity associated with using a wettablemulti-filament yarn. Due to the manufactured tube's relatively smallinner diameter and a sufficiently dense interlacing braid pattern (i.e.,a filamentary wall structure with sufficiently small pore size such thatit retains fluid), a third capillary effect is created. When properlysized, this third capillary effect is responsible for spontaneous flowof liquid inside the micrograft lumen, e.g., within the lumen of thebraid, in a proximal direction. The liquid can also spread in otherdirections as it is absorbed. This structure thus results in a softcapillary tube that has absorbent walls. This triple capillary effect isbeneficial for a vaso-occlusive device due to the fact that the yarns,the fibrous wall, and the micrograft lumen can become saturated withblood. Since blood absorbed by the micrograft is trapped within thestructure, it becomes stagnant and will quickly thrombose or form clot.

To achieve the capillary and clotting characteristics, the micrograft 10achieves an optimal balance of porosity and fluid containment within thesame structure. This is achieved by controlled interlacing ofmicroporous yarns that allow blood wicking and cell ingrowth. Whenbraided with sufficiently high PPI and tension, for example, the porousyarns are able to form a fluid barrier that maintains a degree ofpermeability. The resultant structure (textile tube) is an assembly ofmicro-porous yarns that may be interlaced with sufficient density toform a fluid-tight tubular capillary. This interlacing of the yarns orassembly of filaments can be achieved using textile manufacturingprocesses, such as weaving, knitting, or electrospinning. Porous orsemi-porous filaments may also be used in place of multi-filament yarnsto achieve desired absorbency. Additionally, the micrograft structuredoes not have to include a clearly defined inside lumen to maintaincapillarity, e.g., a defined lumen formed within the wall of the braidor core element, but may alternatively be a porous assembly of fiberssufficiently spaced to allow transport of liquid (much like a suture orstring wicking liquid) or a porous scaffold or biocompatible open cellfoam.

While the semi-porous micrograft 10 as formed as described above has thedesired effect of aiding thrombus formation, it is also relatively stiffas a result of the filaments being closely packed or tightly braided asmentioned above. One benefit of a stiff, denser braid is its ability toretain its non-linear heat-set shape as compared with lower PPI (lessdense) braids. This may facilitate the use of stiffer, higher density 3Dshaped micrografts as framing-type devices used for initial filling ofaneurysm circumference, and then soft and highly compliant micrograftsmay be used as fillers or “finishing” devices towards the end of theembolization procedure. For example, a dense (or high PPI) 2×2(two-over-two) configuration braid may be used as the initial “framing”device whereas a softer and more compliant braid having a lower-PPI 1×2(1-over-2-under-2) configuration braid may be subsequently used to fillthe framed space within the first device. However, even if used as aframing device, excessive stiffness is an undesirable mechanicalproperty for the microcatheter delivery because an overly stiff devicemay cause unwanted movement of the microcatheter tip during deliverywhich can adversely affect navigation of the microcatheter or damagevessels during advancement through the tortuous vasculature. Excessivestiffness is also an undesirable property because stiff devices willconform less to the configuration of the aneurysmal sac and thus preventefficient aneurysm packing.

Therefore, to reduce stiffness to assist delivery and packing of theaneurysmal sac, the micrograft tubular body (braid) 12 is crimped duringmanufacture, i.e., longitudinally compressed and heat set. As the braid12 is compressed, axial orientation of the braided strands is reducedthereby increasing braid angle with respect to the longitudinal axis ofthe tubular body which reduces their influence on overall stiffness ofthe structure, much like a straight wire taking on a more flexible formwhen coiled. Crimping will also effectively increase the PPI, wallthickness, and linear density of the braid by axially compressing thestructure and filament bundles. This compression causes an outwardradial expansion and an increase in wall thickness of the tube. Theresulting braid is much more deflectable, has reduced bend radius, ahigher density and up to 2× to 3× or higher increase in PPI, dependingon braid structure and compressive force applied.

This axial compression also causes the braid structure to “snake” orproduce a spiral wavy form as shown in FIG. 1, which as viewed from theside is a series of macro peaks and valleys, termed “macro-crimps” in asinusoidal shape. The sinusoidal undulations (macro-crimps) aretypically more pronounced in braid structures where the ratio of wallthickness to overall braid diameter is larger (i.e., overall diameterdecreases). Sufficient crimping may also re-orient individual yarn fiberbundles from a mostly flattened (longitudinally organized cross-section)state to a compressed (transversely organized cross-section) state. Thisincreases surface unevenness of the braid since individual yarns bulgeoutward and produce micro peaks and valleys on the braid surface, termed“micro-crimps” (see FIG. 4B for example) with the peaks 17 located atthe height of the yarn and the valleys 19 between adjacent yarns.

The braid can have a series of coaxial aligned filaments and compressedso the filaments orient substantially transversely (with respect to alongitudinal axis of the mandrel).

Different braid patterns (such as 1×1, 1×2, or 2×2, etc.) may alsoproduce varied results when crimped. For example, a 1×1 braid structurewill tend to have a more uniform tubular shape and less distinctivemacro-crimp pattern, whereas a 1×2 braid structure will produce a moresinusoidal (macro peaks and valleys) crimped structure in addition tothe micro peaks and valleys (micro-crimps) of individual fiber bundles.These structural changes result in an ultra-deflectable, increaseddensity, wavy-wall structure having macro-peaks 18 and valleys 20 asshown in the sinusoidal shape of FIG. 1.

Besides increasing braid flexibility, PPI and/or wall thickness, varyingamounts of crimping imparts other potentially desirable features such askink and crush resistance, reduced bend radius, as well as increasedsurface area per unit length via accordion-like compression of the wall(i.e., forming peaks and valleys). The uneven texture of crimped peaksand valleys also helps create localized hemodynamic turbulence and flowstagnation, resulting in improved thrombus formation. The crimps makethe device more compliant, easily deflectable and conformable whichfacilitates packing confined spaces or voids in the vasculature, e.g.,the aneurysm. Crimping may also be used to vary wicking and permeabilityof the textile wall since it reduces fabric porosity and increases yarntortuosity.

The location, amount and magnitude of crimping can be controlled toimpart different amounts of flexibility and elongation to the structureto achieve its desired characteristics. For example, extreme crimpingcan be applied so the braid is compressed until the individual fiberswithin each yarn bundle come together and cannot compress any further,giving the braid some rigidity and improving pushability through amicrocatheter lumen. Other factors that impact crimping and theresulting longitudinal pattern are fiber diameter and stiffness, yarntension during braiding, wall thickness, wall porosity (PPI), number offilaments, and mandrel diameter.

For example, larger diameter, thin walled tubular bodies (braids), i.e.,low wall thickness to outer diameter ratio, may show macro peaks andvalleys which are more dense and visible than small, thick walledcrimped tubes. FIGS. 2A-2C show an example of such large diameter thinwalled tube where crimping can form an accordion-like folds or pleatstructure rather than a sinusoidal configuration as the peaks are closertogether. Crimping smaller diameter braids (braids with higher wallthickness to outer diameter ratios) typically induces a wave-like,sinusoidal longitudinal (macro) contour that is larger in comparison tooverall diameter and increases wall thickness of the structure, as shownin FIG. 16A. It should be noted the sinusoidal contour is typicallythree-dimensional in form (like a spiral) and is visible from all sidesof the braid. During crimping, the ends of the tubular body may also berotated/twisted relative to each other and then heat set as anothermethod to impart deflectability to the tubular body.

The braid 10 can also be made more flexible by varying the braid angleor PPI, by reducing yarn tension, by adding cuts/slits, changing thenumber of filaments or strands, or heat setting repeating patterns alongits length (such as flat sections or kinks). If a stiffer tube isdesired, denser yarn and/or braid pattern may be used or crimpingdecreased. Additionally, the micrograft structure may incorporate acoaxial construction (i.e., having a graft inside a graft) or multi-plyor multi-lumen wall design, especially when using fine-denier textiles.Intra-luminal braid inserts, such as the coils mentioned above, may alsobe composed of, or coated with, a highly wettable/hydrophilic materialto enhance the capillary effect. For example, the micrograft may becoaxially assembled with a secondary braid or internal coil structurethat is highly hydrophilic and/or radiopaque, while maintaining thetherapeutic external surface.

The tubular body 12 may be braided, woven or knitted, partially orcompletely, from monofilaments or multi-filament yarns, strands,sutures, microfibers, or wire that is synthetic, semi-synthetic, naturalor thermoplastic. Such materials may include, but are not limited to,Dacron, poly ester amide (PEA), polypropylene, olefin polymers, aromaticpolymers, such as liquid crystal polymers, polyethylene, HDPE (highdensity polyethylene), ultra-high-molecular-weight polyethylene (UHMWPE,or UHMW), polytetrafluoroethylene (PTFE), ePTFE, polyethyleneterephthalate (PET), polyether ketone (PEK), polyether ether ketone(PEEK), poly ether ketone ketone (PEKK), nylon, PEBAX, TECOFLEX, PVC,polyurethane, thermo plastic, FEP, silk, and silicone, bio-absorbablepolymers such as polyglycolic acid (PGA), poly-L-gllycolic acid (PLGA),polylactic acid (PLA), poly-L-lactic acid (PLLA), polycaprolactone(PCL), polyethyl acrylate (PEA), polydioxanone (PDS) and pseudo-polaminotyrosine-based acids, extruded collagen. Metallic, metallic alloy orradiopaque material may also be included, Such material may be in theform of strands or filaments and may include, for example, platinum,platinum alloys (platinum-iridium or platinum-gold, for example), asingle or multiple stainless steel alloy, nickel titanium alloys (e.g.,Nitinol), barium sulfate, zinc oxide, titanium, stainless steel,tungsten, tantalum, gold, molybdenum alloys, cobalt-chromium,tungsten-rhenium alloys.

The use of different manufacturing methods or materials to construct thetubular body may have an impact on the capillary effects discussedearlier. For example, a change in material or construction methods mayresult in a simple capillary tube with capillary flow restricted to onlythe inner lumen of the tube, and not the walls. It should be understoodby those skilled in the art that strands or filaments may be braided,interwoven, knitted, or otherwise combined to form a fabric or textilestructure.

With reference now to the drawings showing exemplary embodiments of themicrograft of the present invention, the micrograft 10 of FIG. 1, asdiscussed above has a tubular body 12 with a proximal end 14 and adistal end 16.

To provide radiopacity so the device is visible under fluoroscopy(x-ray), the micrograft 10 can include radiopaque marker bands 22 whichare inserted into the ends of the micrograft 10. FIG. 17 is a picture ofan end of micrograft 10 with such marker band. The marker bands, whichcan also be in the form of coils, can be made from tantalum, platinum,platinum alloys (e.g., platinum-iridium alloy), gold, tungsten, or anysuitable radiopaque material such as radiopaque polymer. The markerbands 22 are preferably approximately 1 mm or less in length and can beeither of a sufficient inner diameter to slide over tubular body 12 orof a smaller diameter to fit inside the tubular body 12. FIG. 1 shows anexample of the marker bands 22 fit inside the tubular body and themarker bands 22 can be secured by melting of the braid over the bands(the melted fiber) at region 24, or attached by gluing. The bands 22 canalso be undersized and sliced lengthwise so that they can be swaged orfolded over the outside of tubular body 12, or tubular body 12 can bestretched so that undersized bands can be slid over thestretched/compressed length in order to attach the bands 22 to thetubular body 12. In alternate embodiments, the bands can be flared atone end.

Although two marker bands are shown, in alternate embodiments, there maybe one band or more than two bands placed around the tubular body alongportions of its length to improve radiopacity. The bands positionedalong the length can be in lieu of or in addition to a marker band atone end or a marker band at both ends. A radiopaque fiber can beutilized to connect the bands, and the radiopaque fiber incorporatedinto the textile structure, or placed inside the tube. The bands can becomposed of metal, or alternatively of a non-metallic material such asradiopaque shrink tubing or polymer.

The marker bands can be adhered to the tubular body 12 using adhesive,mechanically by swaging or winding directly on to the tubular body, orby heating (when possible) and melting one of the materials. The bandscan alternatively be attached by being screwed onto or into the coreelement, e.g., a helical core element, as discussed below.

As an alternative or in addition to the marker bands, radiopacity can beobtained by coating, wetting, staining, or impregnating the micrograftwith a radiopaque material such as contrast media solution ornanoparticles. This can be done in manufacturing or in the operatingroom as part of the clinical procedure. The fibers or yarns themselvesmay be doped or impregnated or coated with radiopaque substances asdescribed above. The micrograft may also contain a series of equallyspaces radiodense inserts along its length, resulting in intermittentradiopacity which may be sufficient for visualization in clinicalsettings.

In addition to providing radiopacity, bands 22 can also be used toindicate structural changes in tubular body 12, as a means to controlfraying, or as an integral part of the delivery system (e.g.,stop-collar) as will be better understood in the discussion below of thedelivery of the micrograft.

As another alternate to the bands, laser cut Nitinol structures that aremade increasingly radiopaque can be utilized. These structures can beglued, melted over, sewn or otherwise attached to the proximal and/ordistal ends of the micrograft, either on the inner or outer diameter,and/or attached along a length of the tubular body. Sections of themicrograft or meltable/fusible sleeves of a braided polymer may also beheated and used to adhere bands or other radiopaque structures(components) to the micrograft. Bands or other radiopaque components canalternatively be attached by screwing into the coil windings inside thebraid. The bands or other radiopaque components can either beself-expanding or non-self-expanding. When mated with the delivery wireand pusher catheter described below, they can serve to controlmicrograft linear movement relative to the wire.

As an alternative to the bands for providing radiopacity, a radiopaqueagent as described above could be utilized which would allow completevisualization of the full length of the graft. Another way to providevisualization is the inclusion of a radiopaque coil or insert across theentire length of the inner lumen of the micro-graft. The addition ofsuch coil would make the entire length of the graft radiopaque, however,preferably, to avoid such coil adding an unwanted increase to thestructure's radial stiffness, and to minimize such stiffness whilemaximizing x-ray visibility, such coil may be wound using very thin wiretypically not visible via fluoroscopy, but when coiled with sufficientlysmall pitch (spacing between each loop) it becomes increasingly denseand visible. Pitch of the coil may also vary to make some sections moreradiopaque or flexible than others. The coil can be made of materialssuch as platinum, platinum-iridium, tantalum, gold, silver or otherradiopaque materials used for medical device visualization. The coil canhave a continuous diameter or variable diameter along its length,depending on use. The coil can also be used in combination withradiopaque bands, coatings or as a stand alone radiopaque solution.Insertion of such coils inside the micrograft may also reduce theamplitude of macro-crimps formed during crimping if desired, dependingon radial apposition of coil to braid. It should also be noted thatcoils or other internal inserts may be partially visible through thebraid wall depending on the amount of crimping.

If needed, a simple “J” shape can be heat set into tubular body 12 toaid with introduction into the aneurysm. Agents may also be added to thetube to aid in delivery and/or endothelial cell growth. For example, ahydrophilic coating can be applied to the surface of tubular body 12 toaid in delivery through a microcatheter or a swellable hydrogel infusedwith drugs can be added to provide medicinal treatment and additionalfilling of the aneurysm. Another example is a clotting agent which maybe added to either slow or inhibit the clotting process or to promoteclot formation. Bio-absorbable and biocompatible fibrous elements suchas Dacron (polyethylene terephthalate), polyglycolic acid, polylacticacid, a fluoropolymer (polytetrafluoroethylene), nylon (polyamide) orsilk can also be incorporated into the braid, or to the surface, toenhance the ability of the tubular body 12 to fill space within thevasculature and to facilitate clot formation and tissue growth.Similarly, hydrogels, drugs, chemotherapy beads and/or fibers can beadded to the inner diameter of tubular body 12 or infused into thewalls, yarns, or fibers depending on specific use (for example embolicchemotherapy). On the finishing side of the micrograft (proximal end), amicrocoil (not shown) may be added to provide a barrier between theaneurysm sac and the parent vessel. FIG. 1 can include similar featuresor functions as will be described below.

FIGS. 2A-2C illustrate a micrograft similar to micrograft 10 of FIG. 1except having a larger diameter and thinner wall. FIG. 2A illustratesthe thin walled micrograft 25 crimped in the process described above toforms peaks and valleys resulting in circumferential corrugations orfolds. FIG. 2B is provided for illustrative purposes to highlight thepeaks and valleys by stretching the tubular body. FIG. 2C shows aportion of the micrograft 25 in the bent position. In some embodiments,the micrograft is pre-set in this bend, e.g., a U-shaped configuration,to improve packing within the aneurysmal sac. As shown, due to thestructure of the micrograft, when bent, it maintains its radius in thesimilar manner to a bent coil. (The micrograft would be delivered in asubstantially linear position as described below). As shown, thecompression and heat setting (crimping) process creates an “accordionlike” structure with peaks 18′ and valleys 20′. In FIGS. 2A-2C, the wallof the micrograft 25 is a fine braid, or textile structure, and willapproximate a solid structure when placed in direct blood flow, causinghigh flow disruption. Another feature of the graft is its white color,which may vary depending on PET formulation and processing. If desired,colors other than white may be used to denote different body diametersor transitions in mechanical or therapeutic properties, for example.

FIGS. 4A, 4B, 4D and 4E show an alternative embodiment of the micrograft10′. Micrograft 10′ is similar to micrograft 10 as it formed from abraided tube 12′ and has the same features and functions of tube 12 aswell as can include any of the alternate constructions described herein.Thus, the various descriptions herein of the filaments, yarns, capillaryeffects, shape set, etc., are fully applicable to the micrograft 10′ ofFIG. 4A. However, micrograft 10′ has a core element 27, preferablyformed by a helical coil, having a lumen for blood flow in theaforementioned capillary effect. A tube 29, preferably composed ofNitinol, although other materials can be utilized, is seated withinproximal coils of the tube 29, preferably screwed or twisted into thecoil windings of the helical core element 27. The braid is melted ontotube 29, with region 24 showing the melted fibers, to attach the tube29. Tube 29 has a deflectable tab 29 a and a window 29 b to receive adelivery wire as described below in conjunction with the deliverymethod. The tab 29 a is biased to the aligned position of FIG. 4B and ismoved to an angled position to receive the wire through the window 29 b,the tab 29 a providing an engagement/retaining structure for engagementwith a wire of a delivery system described below. Braided tube or braid12′ is made up of yarns 31 each containing multiple fibers 33. Whenremoved from the braider, the yarn(s) 31 of tube 12′ will lay relativelyflat with the fibers 33 bundled horizontal and spaced apart (see FIG. 4Dshowing tube 12′ positioned over mandrel 35). FIG. 4E illustrates thebraided tube 12′ which has been crimped over mandrel 35 to createcrimped braided tube 12′ prior to formation into the structure of FIG.4A. When the braid is fixed to the mandrel 35 at one or more points anda longitudinal force is applied to the braid, the fibers 33 in the yarn31 will move closer together and bundle vertically creating micro peaks17 and micro valleys 19 (between peaks 17) and corresponding macro peaks18 and macro valleys 20 along the tube length creating a sinusoidalshape (FIG. 4E). (The peaks and valleys of the FIG. 1 embodimentdisclosed herein can be formed in a similar manner). The extent of thepeaks and valleys is dependent on the amount of force applied and thedesired amount of softness. The tube can be completely crimped orselectively crimped at intervals along its length.

In the alternate embodiment of FIG. 4C, instead of a locking tab, amarker band 22′ is attached to the tube to provide retention structurefor engaging structure on the delivery wire. In all other respects, themicrograft of FIG. 4C is the same as the micrograft 10′ of FIG. 4A andhas therefore been labeled with the same reference numerals.

FIG. 3A illustrates another embodiment of an intra-aneurysmalmicrograft. A variable stiffness micrograft 26 with tubular body 28includes the same features and functions as described above with respectto FIG. 1, or its alternatives, e.g., multifilament yarns, capillaryeffects, etc. However, in this embodiment, the micrograft 26, afterforming and crimping, is wound about a mandrel to form a secondary coilshape as shown. This is also shown in FIG. 16B wherein the micrograft 26is pictured both after braiding and crimping (still straight) and afterit's wound into a coil after formation of such braided and crimpedstructure. Other micrografts described herein, with the varying featuresdescribed herein, can also be wound into a coil shape of FIG. 3A ifdesired. The tubular body 28 of micrograft 26 is composed of a variablestiffness braid having a proximal stiff section 30 and a distal flexiblesection 32, the varying stiffness achieved in the ways described above.Tubular body 28 also has a primary diameter D. A radiopaque band 36 canbe provided to allow visualization under fluoroscopy and is shown in theapproximate center of the braid where it transitions in stiffness. Theradiopaque band 36 can alternatively be positioned in other locationsand multiple bands can be provided. Alternatively, radiopacity can beachieved in the various ways described above.

Device 26 is shape-set with heat in a pre-biased (secondary) helicalshape of FIGS. 3A (and 16B.) This is the delivered shape-set form of thedevice 26. This device may not have such pronounced peaks and valleys asmicrograft 10 due to the stretching, bending and heating needed to formsecondary shapes. However, the original crimping operation induces thedesired properties and makes the micrograft more compliant. Partialstretching or partial un-doing of the crimping also results in a braidedlumen that is more compliant radially for improved packing.

Although shown helically-shaped, device 26 can be shape set into anycomplex three dimensional configuration including, but not limited to, acloverleaf, a figure-8, a flower-shape, a vortex-shape, an ovoid,randomly shaped, or substantially spherical shape. As mentioned earlier,a soft, open pitch coil can be added to the inner diameter of the braidto aid in visualization. If stiffness of such metal coil is sufficientlylow, the secondary shape-set of the polymer braid will drive the overallshape of the device. In other words, the secondary shape of the braidmolds the unshaped metal coil which normally shape sets at temperaturesmuch greater than the glass transition temperature of polymers.

The micrograft 26 also has frayed end fibers 38 shown on one end of thedevice. These loose frayed fibers can alternatively be on both ends ofthe braid, if desired (other micrografts disclosed herein could alsohave such frayed ends). When these frayed ends come in contact withanother braid within the aneurysm sac having the same feature, themating ends act like Velcro, allowing the micrografts to interlock andmove together. For delivery and introduction into catheter, device 26would be elongated, e.g., moved to a substantially linear configuration,and inserted into a loading tube having an inner diameter of sufficientsize to accommodate primary diameter D. An optional filament (not shown)may extend from the proximal end of the braid to allowpinching/anchoring of the micrograft between a stent or flow diverterand the parent vessel wall upon release to obstruct flow at the aneurysmneck. Packaging and delivery is discussed in detail below.

FIG. 3B illustrates another embodiment of an intra-aneurysmalmicrograft. Sliced micrograft 40 has a tubular body 42 that can includethe same features and functions as described above for the previousembodiments, e.g., multifilament yarns, capillary effects, etc. Tubularbody 42 has a longitudinal cut 44 and is shape set to expose its innersurface 46, thereby providing a flared distal end. Micrograft 40 isconfigured with a portion of the inner diameter exposed to maximizesurface area constricted by flowing blood and to aid in movement withblood flow. Device 40 can include a proximal marker band 48 (oralternatively any of the other aforedescribed radiopaque features) forvisualization. Holes 50 and 52, formed by laser cut or other methods,provide for communication with the blood. Micrograft 40 is particularlysuited for placement at the neck of the aneurysm either manually with adelivery system or through movement with blood flow circulating withinthe aneurysm. Delivering micrografts 46 to an aneurysm may result inclogging at the neck/stent interface as they get caught up in exitingblood flow and accumulate at the aneurysm neck. This structure can alsobe a round tube, flattened tube, or other shape that is easily moved byblood flow.

The tubular bodies for the above embodiments have been described ascrimped braided tubes, however, the tubes can be made using othermanufacturing methods such as weaving, knitting, extruding, orelectro-spinning. Structures can also be manufactured with alternatingdiameters or cross-sections, such as flat to round. In addition, thetube can be made from a rolled sheet or other material formed intodesired tubular or substantially cylindrical structures. Structuralflexibility can then be adjusted either by crimping or selective lasercutting, for example. If desired, the tubular body can also be flattenedto create a thin walled tape or heat pressed to create oval sections.

Also, although crimping, or the use of axial/longitudinal compressionand heat is described to produce crimps or peaks and valleys, othermanufacturing methods of constructing peaks and valleys can be utilizedto achieve similar effects. For example, a wire may be wound tightlyaround a braid placed on a mandrel. The gaps between windings willcreate peaks and when the assembly is heat set (with or withoutlongitudinal compression) and the wire removed, valleys will be formedwhere the wire compressed the braid and peaks where the braid wasexposed.

FIGS. 16A through 16C and FIG. 17 illustrate a portion of micrograft 10tubular body 12 constructed of 20 denier/18 filament polyester yarn.FIG. 16A shows examples of an uncrimped tubular body 171 alongside acrimped micrograft 10 tubular body 12 to illustrate the formed macropeaks and valleys. FIG. 16B shows a crimped tubular body alongside atubular body that has been shape set into a helical coil 172 postcrimping similar to FIG. 3A. FIG. 16C shows micrograft 10 that has fluid174 which has been drawn into the micrograft via capillary actiondescribed earlier. FIG. 17 shows a tubular body with a marker band (stopcollar) 22 attached to the body as in FIG. 1.

Turning now the delivery of the micrografts, several embodiments ofdelivery systems of the present invention are disclosed. Many of thedelivery systems enable over the wire insertion which minimizesmicrograft snaking inside the catheter as well as enables delivery oflonger length micrografts. The delivery systems also enableretrievability of the micrograft after partial deployment, and in someembodiments, even after full deployment.

Turning to a first embodiment and with reference to FIGS. 5A-5D, anintra-aneurysmal micrograft delivery system is illustrated anddesignated generally by reference number 54. The delivery system isdescribed below for delivering micrograft 10 but it should be understoodthat it (as well as the other delivery systems described herein) can beused to deliver any of the micrografts disclosed herein. Delivery system54 includes a pre-loaded delivery wire 62 for carrying the micrograftand a pusher catheter 58, the pre-loaded delivery wire 62 positionedwithin the pusher catheter 58. Optionally the system could include aloading sheath similar to the loading sheath of FIG. 7 described belowwhich is positioned thereover to retain the micrograft on the deliverywire 62. The individual components of the delivery system can be removedfrom the packaging during the procedure and assembled by inserting thedelivery wire 62 proximally through the catheter 58 creating a junction57 at the proximal end of the micrograft 10 and the distal end of thepusher catheter 58. Alternatively, they can be pre-packaged with thedelivery wire 62 already positioned within the pusher catheter 58 and aprotective loading sheath similar to the loading sheath of FIG. 7positioned thereover to retain the micrograft 10 on the delivery wire62. This delivery system may be used as a standalone delivery system toaccess the target anatomy, or with a microcatheter as described below.Any necessary flushing or coating activation can be done per physician'sdiscretion prior to insertion into the patient.

Delivery wire 62 has micrograft 10 mounted thereon at region 56.Delivery wire 62 has a body with a length extending from proximal end 64to distal end 66 can range between about 20 cm and about 400 cm, andmore particularly between about 100 cm and about 300 cm, and even moreparticularly about 200 cm. Suitable diameters for the delivery wire 62can range from about 0.0025 inches to about 0.040 inches, and morenarrowly between about 0.002 inches and about 0.035 inches. The overalldiameter of the delivery wire may be continuous, for example about0.014″ or the wire may taper from proximal to distal direction, forexample about 0.007 inches to about 0.003 inches. Other sizes are alsocontemplated, dependent on the pusher catheter and/or microcatheter IDused for the procedure.

The distal portion 68 of the delivery wire 62 can include a coil and thevery distal tip 66 of delivery wire 62 can be bulbous, of increaseddiameter, or fitted with a marker band or coil. The distal portion 68 ofthe delivery wire may be radiopaque as well as able to be shape set toaid in tracking, vessel selection, and intra-aneurysm maneuvering. Forexample the distal portion can be shape set to J-shape as in FIG. 11Adescribed below. The delivery wire 62 may also be coated with ahydrophilic coating. The delivery wire 62 includes a retaining structuresuch as a tapered region to aid in retention of the micrograft 10thereon. In alternative embodiments, to further aid retention, or if adelivery wire is utilized which does not have such retention structuresuch as a standard guidewire, then a protective loading sheath can beutilized. In another embodiment, the micrograft can be mounted using themicrograft introducer system 136 as described below with regard to FIG.9.

Delivery wire 62 has a tapered region 70 (FIG. 5C) forming an engagementstructure for mounting the micrograft 10. A proximal stop collar 22 ispositioned over the tapered region 70. The stop collar 22 can beattached to the delivery wire 62 or alternatively and preferably form aretaining feature attached to an internal portion of the micrograft 10.In either case, the proximal end of the micrograft 10 is frictionallyengaged and retained by the delivery wire 62. Micrograft 10 is mountedcoaxially (and slidably) on wire 62 a distance L from the wire distaltip 66. The distance L is set by the proximal stop collar 22 whichinteracts with wire taper 70 as shown in FIG. 5C, or other hard stop onthe wire (e.g., a marker band), and the overall length of themicrograft. For instance, longer micrografts may have a small distanceL. In some embodiments, distance L may be zero and the hard stop may beon, inside or near the distal end of the micrograft 10 to interact witha bump, bulb or head (such has a head 184 of FIG. 5E described below) onthe distal end of the delivery wire 62 to prevent the delivery wire 62from passing through the distal end of the graft. In this instance, thedistal tip of the micrograft 10 would be adjacent the distal end of thedelivery wire 62 as in the embodiment of FIG. 5E.

FIG. 5C shows an enlarged cross sectional view of the proximal end ofmicrograft 10 with stop collar 22 engaging tapered region 70 of thedelivery wire 62. The stop collar 22 as shown is in the form of a markerband to provide radiopacity for visualization. The wire taper 70 acts asa proximal stop to prohibit proximal movement of the micrograft 10 overthe wire 62.

Other ways to couple or mate the micrograft and the delivery wire 62 arealso contemplated. As mentioned earlier, proximal and distal Nitinolparts may be added to the micrograft as stops, or other parts and/orfeatures (e.g., platinum marker band, notch, bump, etc.) can be added tothe delivery wire to act as stops. In some instances, there may be nostop collar, the stop may be on the distal end of the braid (asmentioned above), the pusher catheter may act as the proximal stop, orthe micrograft 10 can be sized to be free to slide across the entirelength of the delivery wire, proximal to distal.

The pre-loaded delivery wire 62 may be supplied with one or moremicrografts covered by a protective cover such as cover 92 of FIG. 7.This cover 92 has a tapered tip tapering to a smaller outer dimensionfor introduction into the lumen of a microcatheter or component thereof.

In some embodiments, more than one micrograft can be loaded on thedelivery wire. They can be linked together on the delivery wire fordelivery using one of the frayed, Velcro-like ends 38 described abovewith respect to FIG. 3 or inter-connected with assistance of the coaxialdelivery wire running through them. That is, the device can in someembodiments be supplied pre-packaged with a plurality of micrografts inline along the delivery wire.

As mentioned above, the delivery system 54 includes a pusher catheter 58having a lumen through which the delivery wire 62 extends. Pushercatheter 58 includes a catheter body 72 and a Luer lock 74. Catheterbody 72 is preferably of a variable stiffness construction with a stiffproximal section, softer mid-section and still softer distal section.Individual sections of the catheter may be made up of polymer tubingwith varying durometers to control stiffness, proximal to distal. Thebody may also be made from a variable stiffness, laser cut tube made ofstainless steel alloy or Nitinol, for example. If polymer tubes areused, the catheter may also be a braid or a coil reinforced to keep fromovalizing. A lubricous liner made from materials such as PTFE, ePTFE, orFEP may also be added to the structure.

The outer diameter of the pusher catheter 58 is dimensioned to slidefreely inside microcatheters with inner diameters ranging from about0.008 inches to about 0.070 inches. Catheter body 72 can include ahydrophilic coating on its outer diameter for lubricity. The length ofthe catheter body 72 is preferably slightly shorter than the deliverywire 62 to allow proximal access to the delivery wire 62, i.e., holdingthe wire 62, while a micrograft (or multiple micrografts) is loaded onthe distal end. The inner diameter of pusher catheter body 72 or thedistal end is sized and shaped so that the micrograft 10 cannot beforced inside the catheter body 72 during distal advancement or proximalpulling of delivery wire 62. When loaded in the pusher catheter 58, thedelivery wire 62 is preferably free to rotate and to move in a linear(back and forth) motion relative to the pusher catheter 58.Additionally, the pusher catheter 58 can be designed to accommodatedelivery of stents or other devices or fluids to the target anatomy. Insome embodiments, a clearance between an outer dimension of the deliverymember and an inner dimension of the occluding device is substantiallyfluid-tight before delivery into the aneurysm but sufficient to enableslidable movement of the delivery member with respect to the occludingdevice.

At or near the distal end of pusher catheter body 72 is radiopaquemarker band 76 which can be made of platinum/iridium and attached withadhesive, heat shrink tubing, a swaging process, or other known methods.Alternatively, the marker band can be placed inside the pusher catheter58 with the delivery wire 62 passing through it. Other suitableradiopaque materials for marker band 76 include gold, silver, andradiopaque shrink tubes, or metal coils for example. A luer lock 74 canbe positioned at the proximal end of the catheter 58 and attached to theluer lock 74 is a rotating hemostatic valve (RHV) 78 for saline, drug,contrast media or other fluid introduction though the inner diameter ofpusher catheter 58. The RHV 78 also serves as a lock to stop relativemovement between the pusher catheter 58 and the pre-loaded delivery wire62 when the RHV 78 is tightened over (clamped onto) the wire. In someembodiments, the pusher catheter 58 can be delivered pre-packaged andsterile with an RHV as an accessory. In embodiments where a co-axialcatheter stent delivery system is used, a pusher catheter may not berequired as after stent deployment by the stent delivery catheter, themicrograft loaded delivery wire can be inserted into the stent deliverycatheter to deploy micrografts.

As described earlier, the delivery wire 62 may be used as the primaryaccess wire as in conventional guidewires. FIG. 6 illustrates analternate design to the over-the wire pusher catheter, which is a rapidexchange pusher catheter designated generally by the reference number80. The rapid exchange (RX) pusher catheter 80 has a catheter body 82with marker band 76 at a distal end and a stiff push wire 84. Catheterbody 82 will share many of the same features as the mid and distalsection of catheter body 72 described above, including coating. Thestiff pusher wire 84, which may taper, can be made of stainless steelalloy, Nitinol, or other suitable material. The pusher wire 84 mayalternately be a hypo-tube, with or without laser cutting, or a wirefeaturing a non-round cross-section. The device may be suppliedpre-packaged and sterile. In use, the RX catheter may be inserted overthe delivery wire or guide wire before or after the aneurysm is accessedby the wire.

FIG. 5E-5G illustrate a delivery system 180 for delivering themicrograft 10′ of FIG. 4A. The delivery system has a pusher member 186and delivery wire 182 with an enlarged head 184. In the initial positionof FIG. 5E the tab 29 a of micrograft 10′ is bent downwardly and thedelivery wire 182 passes through window 29 b. The delivery wire 182extends within micrograft 10′ to the distal end of the micrograft 10′.In this position, head 184 engages the proximal edge of stop 22, e.g.,distal marker band 22, on micrograft 10′.

The pusher member or catheter 186 has an internal stop 188 at its distalend to aid with pushing micrograft 10′ as well as to inhibit movement ofmicrograft 10′ into the pusher member's inner diameter. The pushercatheter 186 is shown by way of example without a luer attachment. Boththe pusher catheter 186 and the delivery wire 182 may be constructed aspreviously described. In addition, although not shown, system 180 caninclude a protective introducer sheath similar to the loading sheath 92of FIG. 7 to limit micrograft movement as well as to assist inmicrograft introduction into a microcatheter.

In the initial position, tab 29 a of micrograft 10′ is bent downwardlyand the delivery wire 182 passes through window 29 b (FIG. 5E). Thedelivery wire 182, as mentioned above, extends inside the graft 10′ suchthat enlarged head 184 comes into contact with the proximal edge of stop22. Note, although the stop 22 is shown as open, it may be completelyclosed. Also, the stop may be excluded and the braid may be melted tonarrow or close the distal end of the braid to prohibit the wire 182from exiting. The use of a distal stop also serves the purpose ofkeeping the micrograft 10′ in tension which aids in delivery bystretching and reducing the outer diameter of the micrograft 10′.

The tab 29 a provides a force against the delivery wire 182 to retainthe micrograft 10′ on the wire 182. Upon delivery, the wire 182 isretracted to the position of FIG. 5F where delivery wire enlarged tip184 engages the tab 29 a. Up to this position the micrograft 10′ can beretrieved from the aneurysm and/or maneuvered therein. Next, pushercatheter 186 is advanced (or wire tip retracted) to force the tab 29 ato the position of FIG. 5G, therefore enabling full retraction of theenlarged head 184 of the delivery wire 182 through window 29 b forrelease of the micrograft 10′ from the delivery wire 182. FIG. 5H showsthe tab 29 a returned to its original position longitudinally alignedwith the micrograft 10′ after retraction of the delivery system.

FIG. 7 illustrates another embodiment of an intra-aneurysmal micrograftdelivery system generally referred to by reference number 86. Deliverysystem 86 comprises a pusher wire 88 and a loading tube 92. Pusher wire88 includes an elongate tapering flexible wire that can be made fromstainless steel, or alternatively, Nitinol, plastic or other inert orbiocompatible material or combination thereof. Although shown as a wire,the pusher wire can alternatively be a hypo-tube with a Luer lock.

At the distal end of pusher wire 88 are expanding grasper members orarms 94, 98. Although there are four grasper arms in this design, moreor less than four arms may be used. The arms 94, 98 can be made of shapeset shape memory material such as Nitinol, spring tempered stainlesssteel, radiopaque metal, or other suitable material. The arms 94, 98 canalternatively be manufactured from a metal or elastic tube which islaser cut to create deflectable arms. Attached to the distal end of oneor more of the grasper arms are radiopaque bands (see labeled bands 102,106, and 108; the fourth band not shown since the fourth arm is notshown). The bands can be attached with glue, solder or other methods.The proximal ends of the arms are attached to the pusher wire 88 by acoil 110 which can be made of wound stainless steel or platinum iridium,for example. Attachment methods may include gluing, welding, orsoldering. The use of the grasping arms has the advantage of enablinggrasping of the micrograft after full deployment to retrieve/remove themicrograft or to maneuver/reposition the micrograft within the aneurysmas described below.

The pusher wire 88 has a length (including arms) between about 20 cm andabout 400 cm, more narrowly between about 100 cm and about 300 cm, forexample about 200 cm. Suitable diameters for the pusher wire 88 canrange from about 0.006 inches to about 0.040 inches, more narrowlybetween about 0.008 inches and about 0.035 inches. The overall diameterof the pusher wire 88 may taper from proximal to distal, for exampleabout 0.014 inches tapering to about 0.003 inches. The pusher wire 88,either in part or whole, may be coated with a hydrophilic or PTFEcoating for lubricity

Loading tube 92 is made of either metal or plastic and preferably hasdistal taper 112 for mating with a microcatheter Luer taper. The loadingtube 92 preferably has a length sufficient to cover the entiremicrograft 90 and at least a portion of coil 110. The inner diameter ofthe loading tube 92 is preferably close to the inner diameter of themicrocatheter to which it will mate. A range for the inner diameter maybe between about 0.008 inches and about 0.070 inches. The loading tubemay have a crimp or other fixation method to prevent relative movementto the pusher wire 88. If used on a structure having a Luer or otherattachment on its proximal end, the introducer may have a lengthwiseslit to aid in removal (i.e., peel-away).

One way to load micrograft 90, which has proximal band 114, e.g., amarker band, is to position the loading tube 92 on pusher wire 88 justproximal to the two pair of grasper arms 94, 98 so that the arms are intheir normal expanded position. The band 114 on micrograft 90 is thenpositioned between bands 102 and 104 (one on each arm of arms 94) andbands 106 and 108 of arms 98. Note to achieve axially spaced bands, thearms 94 can be shorter than arms 98 so the bands 102, 104 are proximalof bands 106, 108, or alternatively, the arms 94, 98 can be the samesize and bands 102, 104 can be placed on a more proximal position ofarms 94 (spaced from the distal end) while bands 106, 108 can be placedon a distal end or more distal position of arms 98. The loading tube 92is then advanced forward (distally) compressing the pusher arms 94, 98to a collapsed or compressed position to engage (grasp) the band 114 toretain the micrograft 90 in place. Thus, band 114 forms an engaging orretention structure for engagement by the pusher (delivery) wire 88 toretain the micrograft 90 on the wire 88.

Note micrograft 90 is similar to micrograft 10 except for the proximalband 114 which is positioned around a portion of the braided structure.

Note alternatively, instead of the micrograft having a single proximalmarker band, it may have two proximal bands where the bands of thepusher wire sit to create a lock when compressed inside the lumen of theloading tube. Alternatively, a micrograft with an internal coil may haveproximal coil windings spaced to have a gap that allows radialcompression and grasping by the bands of the pusher wire.

FIG. 8 illustrates yet another embodiment of an intra-aneurysmalmicrograft delivery system generally referred to by reference number116. Delivery system 116 is a neurovascular stent-graft kit thatcomprises a pusher wire 118 with distal band 120, stent or flow diverter122 with proximal arms with bands 124 and 126 and distal arms with bands128 and 130, micrograft 132 with proximal band 134, and loading tube133. The micrograft 132 is locked proximally by the stent 122 and stentbands 128 and 130 and loading tube 133. Stent or flow diverter 122 is inturn locked to pusher wire 118 using a similar locking concept as bands124, 126 are blocked by band 120. The number of arms for both lockingsystems may vary to be more or less than two. Delivery system 116 canalso be configured to have a through lumen for guidewire delivery.

The delivery system 116 provides a single delivery system that candeliver a micrograft and a stent that can be combined on site to form aneurovascular stent-graft. Alternately, the stent may be permanentlyattached to the pusher wire and acts as a temporary stent to push graftsinto the aneurysm.

FIG. 9 illustrates a micrograft introducer system 136 which may be usedto mount micrografts on a delivery wire or on a guidewire before orduring a medical procedure. Micrograft loader introducer system 136comprises introducer sheath 138 loaded with micrograft 10. Theintroducer sheath includes tubular body 140, Luer lock 142, and stoptube 144. Tubular body 140 can be made of metal, plastic or acombination of materials and sized with an inner diameter between about0.008 inches and about 0.070 inches and a length that covers all orsubstantially all of the micrograft 10. The distal tip of the tubularbody 140 may be straight or tapered to help in micrograft introductionand handling. The Luer lock can be attached to an RHV such as RHV 78 ofFIG. 5D for the introduction of fluid such as, saline or contrast media,guide or delivery wires and pusher catheters. The stop tube 144, whichis optional, has a through lumen and can be made of plastic or metal andmay have a taper proximal to distal. The purpose of the stop tube is toprohibit the micrograft from exiting the tubular body 140 prior toloading and may be removed prior to insertion.

Although FIG. 9 shows only one micrograft, multiple micrografts may bedelivered in a single introducer sheath. They may be free to moverelative to one another or linked together using the frayed ends method,for example, as described above. Micrografts having secondary shapeswill generally be linear or straight when loaded into the introducersheath such that they are concentric.

Introducer system 136 is delivered pre-packaged and sterilized. Onceopened, an RHV and syringe may be attached to the Luer to introducefluids. A delivery wire or guidewire may be pushed into the introducersheath 138 to mount the micrograft(s) on the wire or alternatively theintroducer sheath 138 may be mated with the proximal end of themicrocatheter and the micrografts may be pushed proximally through thesheath 138 and into the microcatheter using a pusher catheter, with orwithout a wire, or with a commercially available pusher wire.

The micrografts disclosed herein can be preset to a non-linearconfiguration and advanced to the aneurysm in a substantially linearconfiguration and then return to the same non-linear configuration ordifferent non-linear configuration when delivered into the aneurysm,depending on the space within the aneurysm.

FIGS. 10 through 11F show the preferred method of using intra-aneurysmalmicrograft delivery system 54 of FIG. 5A to deploy micrograft 10 ofFIG. 1. (Other micrografts described herein can be inserted in a similarfashion). The micrograft delivery method, as well as the “viscositylock” function (described below) are depicted in flow chart form inFIGS. 18 and 19. Before implantation, the delivery system may beprepared prior to patient insertion as described above or as preferredby the physician.

Typical intracranial aneurysm access requires inserting a guide catheterinto the femoral artery and then tracking a microcatheter in combinationwith a primary guidewire through the vasculature until the aneurysm siteis reached. Once there, the primary guidewire is removed and replacedwith an embolization system. FIG. 10 shows micrograft delivery system 54of FIG. 5A being inserted as a unit into the proximal end ofmicrocatheter 146 (with attached RHV 148), the microcatheter 146 havingbeen inserted through the guide catheter and advanced to the aneurysmsite and the primary guidewire removed.

FIG. 11A illustrates the distal tip 66 of delivery wire 62 exitingmicrocatheter 146 that has been positioned inside aneurysm 150 and isheld in place using a “jailing” stenting technique, surrounded by blood152. Jailing refers to the use of a stent or flow diverter 154 to pinthe distal tip of the microcatheter between the parent vessel intima andthe stent or flow diverter 154, so that the microcatheter tip is heldwithin the aneurysm and delivered occluding devices, e.g., micrografts10, are kept out of the parent vessel lumen. Other techniques that maybe used instead of jailing include temporary stenting and balloonremodeling. It is also contemplated that the micrografts of the presentinvention be deployed without the use of such parent vessel support(stent or flow diverter) devices.

Once the system is in place as shown in FIG. 11A, the exposed deliverywire tip 66, which has the pre-bent curve as shown, is slowly retractedinto the micrograft 10. The retraction can be done in incremental stepsof a few centimeters or completely until it reaches a location at, ornear, the pusher/micrograft juncture 57 (see FIG. 5A). As the deliverywire 62 is retracted proximally toward junction 57, blood 152 will bedrawn into the micrograft's inner lumen to fill the volume previouslyoccupied by the delivery wire 62, as depicted in FIGS. 11B and 11C. Thisfilling action occurs through a combination of the unique internalcapillary features of the micrograft described earlier and due to asyringe-like “piston” effect of the receding wire.

With the delivery wire 62 pulled back and in some embodiments pulledback to a locked position against tab 21 a, as in the embodiment of FIG.5F, the micrograft 10 can be pushed forward off the wire 62 and into theaneurysm as illustrated in FIG. 11D using the pusher catheter 58 (FIG.5A) as it is advanced distally and engages the proximal end of themicrograft 10. Note that if the delivery system does not feature amechanical lock physically connecting the pusher catheter 58 or deliverywire 62 to the micrograft 10, the micrograft 10 may still be retrieveddue to a “viscosity lock” (described below) that is formed inside themicrocatheter 146, between the delivery system components andmicrograft, once surrounded by a viscous liquid (e.g., blood). This lockallows the micrograft 10 to be advanced and retracted while the proximalend of the micrograft 10 remains inside the lumen of the microcatheter146 until desired placement is achieved.

Micrograft 10 is pushed forward by pusher catheter 58 and the wire 62can be pulled further proximally to junction 57, if it is not positionedthere already. Once the wire 62 reaches junction 57, the inner lumen ofthe micrograft 10 will be completely filled with blood 152 thatdisplaces the wire 62 and with any liquid that has been present (e.g.,contrast). Since blood now fills the inside lumen of the micrograft 10and has already permeated the braided walls via the aforedescribedcapillary action, the saturated device is composed in part of thepatient's blood. Thrombosis and cell in-growth through the microporousyarns will be accelerated as the blood becomes trapped and stagnantwithin the micrograft (implant) after delivery.

Note that blood can enter the lumen of the micrograft 10 through adistal opening of the lumen and/or through other intermediate orproximal regions of the lumen spaced from the distal end as blood isabsorbed through the braided structure. As blood enters suchintermediate or proximal regions, it spreads in various dimensions aswell as is directed proximally due to the aforedescribed capillaryaction.

As the micrograft 10 is deployed into the aneurysm, it will take on anypreset secondary shapes and random shapes due to contact with aneurysmwalls or the stent/flow diverter 154, as shown in FIGS. 11D and 11E.That is, in these Figures, micrograft 10 has a pre-set U-shape as shown,however, this shape can change as it contacts the aneurysm wall and/orstent 154. If the proximal end of micrograft 10 remains inside themicrocatheter, the micrograft 10 can be retracted and repositioned atany time prior to full deployment as described above. The micrograft 10will be fully deployed and disengage from the delivery system once thedistal tip of the pusher catheter 58 reaches or exits the distal end ofthe microcatheter 146. FIG. 11E shows an enlarged cross section of thefully deployed pre-shaped blood filled micrograft 10 of FIG. 11D.

After the first micrograft 10 has been deployed, the delivery wire 62and pusher catheter 58 are removed and, if needed, another micrograft 10is loaded on the wire 62 or a new delivery system is opened, and thedeployment process is repeated as described above. Multiple micrograftscan be deployed by repeating the above steps until the aneurysm issufficiently packed (per physician discretion) as shown in FIG. 11F. Ifneeded, the microcatheter tip or the delivery wire 62 can be used inbetween packing or during packing to move or compress micrografts withinthe aneurysm. Once the aneurysm is sufficiently packed, themicrocatheter is removed and the stent or flow diverter 154 continues toexpand to cover the neck of the aneurysm 158 to thereby block exit ofthe micrografts 10 from the aneurysm sac. Together, micrograft 10 andstent or flow diverter 154 form neurovascular stent-graft 160, as shownin FIG. 11F.

As mentioned above, delivery system 54 features a temporary liquid sealor “viscosity lock” effect inside the microcatheter which allows limitedretrieveability (push/pull) of the micrograft during placement. The“pull” of the lock is generated by the tip of the pusher catheter 58,which creates a syringe-like “piston” within the fluid-filledmicrocatheter 146. Functionality of this lock is dependent on clearancesbetween the microcatheter lumen, proximal micrograft 10 body, adjacentpusher 58 tip, the delivery wire 62, as well as the viscous and cohesiveproperties of the fluid medium.

The flow chart of FIG. 19 describes the steps of the viscosity lockfunction which are as follows:

-   -   1) Inside the aneurysm, align tip of delivery wire 62 with        distal end of micrograft 10.    -   2) Retract wire 62 to draw blood inside micrograft lumen up to        the pusher junction 57.    -   3) Push delivery system (pusher 58+wire 62) to advance        micrograft 10 out of catheter 146.    -   4) While maintaining proximal end of micrograft 10 inside        catheter 146, pull on delivery system to retract micrograft 10.    -   5) Re-deploy micrograft 10 once re-positioned by pushing on        delivery system.    -   6) Release blood filled micrograft 10 by pushing proximal end of        micrograft 10 out of catheter 146.    -   7) Repeat process to deliver another micrograft 10, or remove        delivery system and load additional micrograft 10 onto distal        wire tip.

In order for the viscosity lock to work, viscous liquid (i.e., blood)must fill the microcatheter past the micrograft/pusher junction. Onceviscous fluid fills the micrograft(s) 10 and gaps around the pusherjunction 57, it acts as a “gasket”, or a seal, around thepusher/micrograft junction 57 during any displacement (i.e., as thepusher is retracted). The action of pulling the pusher 58 (i.e., thepiston) adjacent to the proximal end of the micrograft now creates a lowpressure volume. This causes the micrograft(s) 10 suspended in blood toget suctioned and retract within the microcatheter 146.

The micrograft 10 may also be retractable if the delivery wire distaltip 66 is pulled back proximal to the distal tip of pusher 58 or removedcompletely. High friction or pull resistance are more likely to breakthe “viscous lock”, so the preferred application for this retrievalmethod is with shorter, lower friction devices or where minimaltortuosity and resistive forces are involved.

In some embodiments of the micrograft delivery system, a pusher wire ordelivery wire may not be present inside the micrograft lumen andinternal filling of the micrograft with blood will be induced bypressure from the patient's circulatory system or via capillary forces.Capillarity can be achieved by the micrograft having appropriately sizedinner diameter or pores, as described earlier. Hence, the absorption ofblood into micrograft depicted in FIG. 11C can occur upon contact withblood even if delivery wire or external force is not used to draw bloodin.

FIGS. 12A through 12C show directed delivery of micrograft 10 of FIG. 1inside an intracranial aneurysm. Other micrografts described herein canbe delivered in a similar manner. Unlike micrograft delivery describedin FIGS. 10 and 11A-11F above, in the embodiment of FIGS. 12A and 12B,the shaped delivery wire 62′ remains in the aneurysm so that themicrograft deployment can be directed to a targeted location (neck)within the aneurysm sac. FIG. 12A illustrates a distal tip 66′ ofdelivery wire 62′ that has been shape set in a “J” and deployed so thatthe “J” points at the stent or flow diverter 154 covering the neck ofthe aneurysm. As the pusher catheter 58 is advanced distally, themicrograft 10 will deploy and follow along the delivery wire 62′ in adirection denoted by arrow 162 towards the stent or flow diverter 154.

FIG. 12B illustrates a delivery wire 62′ that has been shape set with a“J” and advanced into the dome of the aneurysm. As the micrograft 10 isadvanced it will follow the curvature of the wire 62′ in a directiondenoted by arrow 164.

FIG. 12C illustrates that the microcatheter 146 can be used to directmicrograft deployment within the aneurysm. The delivery wire has beenpulled back into microcatheter 146 which is seated in the neck of theaneurysm 158. As the micrograft 10 is advanced it will follow thedirection denoted by arrow 166. The tip of the microcatheter 146 can becurved to direct the micrograft 10. When the micrograft 10 encountersbarriers, such as the aneurysm wall, it will easily change direction asdepicted.

FIG. 13 illustrates the deployment of flow directed micrografts 168using intra-aneurysmal micrograft delivery system 54 with delivery wire62′ having a “J” form at its tip and extending from microcatheter 146.Micrografts 168 can have the same structure as other micrograftsdescribed herein. Flow directed micrograft 168 can be any length, butshorter lengths such as about 2 mm to about 5 mm are utilized in thisembodiment so as to move with blood flow. Since the flow directedmicrografts 168 tend to be shorter than micrografts configured to fillthe aneurysm, many more flow directed micrografts can be loaded onto thedelivery wire and consecutively deployed, as illustrated in FIG. 13.Micrograft 168 has been shape set into a “C” shape, however, othershapes are also contemplated as discussed above.

As each micrograft 168 is advanced distally off the delivery wire 62′,it will be caught up in blood flow exiting the neck of the aneurysm. Dueto the stent or flow diverter 154 blocking the neck 158, micrograft 168will be restricted from exiting into parent vessel 170. When asufficient amount of micrografts 168 are introduced into the aneurysm,the micrografts will pile up and clog or create a localized graft at thestent/flow diverter and neck interface. Over time, thrombus will formabove the clog to aid in closing off the aneurysm. The smaller, shortermicrografts are intended to provide a more complete obstruction or fillvoids at the aneurysm neck.

FIG. 14 illustrates microcatheter 146 positioned inside the parentvessel 170. This embodiment differs from the previous embodiments inthat instead of extending in the space between the stent 154 and parentvessel 170, the microcatheter 146 extends through the struts or pores ofstent or flow diverter 154. In all other respects, the system is thesame as that of the aforedescribed systems. Note micrograft 10 is shownexiting the microcatheter 146 into the aneurysm. Longer length orshorter length micrografts can be delivered.

As discussed earlier, the delivery wire 62 can be a guidewire.Therefore, if desired, the micrograft delivery system with guidewire canbe loaded into the microcatheter prior to catheter placement. The entireassembly, microcatheter and micrograft delivery system, can then betracked to the aneurysm site using the delivery system's guidewire asthe primary tracking wire. Alternately, the guidewire and microcathetercan be tracked to the aneurysm site and rapid exchange catheter, e.g.,pusher catheter 80 of FIG. 6, can be advanced subsequently.

FIG. 15 illustrates the distal end of intra-aneurysmal micrograftdelivery system 86 of FIG. 7 deploying micrograft 90. Micrograft 90 hasbeen released from arms 94, 98 and has assumed a pre-biased (pre-set)shape. As noted above, the micrografts can be pre-set to a variety ofconfigurations and the shapes illustrated in the drawings are providedby way of example. If desired, the micrograft 90 can be retrieved bycapturing a portion of the structure between arms 94, 98, and advancingthe microcatheter 146 over the arms to compress the arms. Alternately,the delivery arms 94, 98 can be used to compress or move the micrograftaround the aneurysm to aid in packing.

FIG. 18A provides a flow chart for one method of placing a micrograft ofthe present invention. This method utilizes the delivery system of FIGS.5A and 5C. The steps include:

-   -   1) Insert micrograft(s) over distal end of delivery wire 62        until micrograft rests on stopper or wire taper 70.    -   2) Insert delivery wire 62 into pusher catheter 58.    -   3) Insert delivery system into RHV 78 of microcatheter.    -   4) Track delivery system until wire tip 66 reaches aneurysm.    -   5) Pull back wire 66 and align with distal marker band of        micrograft in aneurysm.    -   6) Fill micrograft with blood by retracting wire tip 66 into the        micrograft.    -   7) Deploy micrograft by advancing pusher 58. Retract device if        proximal end still in microcatheter.    -   8) Remove delivery system from microcatheter.    -   9) If needed, repeat steps to deploy additional micrografts.

FIG. 18B provides a flow chart for another method of placing amicrograft of the present invention. This method utilizes the samedelivery system of FIGS. 5E-5H. The steps include:

-   -   1) Remove device from packaging and prepare per Instructions for        Use (IFU).    -   2) Insert delivery system with micrograft into microcatheter        RHV.    -   3) If present, remove introducer sheath once micrograft is        inside microcatheter.    -   4) Track delivery system until wire tip 184 and distal end of        micrograft reach the treatment site.    -   5) Fill micrograft with blood by incrementally retracting wire        tip 184 just distal of the micrograft lock (tab 29 a).    -   6) Deploy micrograft by advancing delivery system (pusher 186        and wire 182). Pull delivery system to retract micrograft if        necessary.    -   7) Once out of microcatheter, detach micrograft by retracting        wire 182 (or advancing pusher) until wire bulb 184 pulls through        micrograft lock (tab 29 a) and into the pusher 186.    -   8) Remove delivery system from microcatheter.    -   9) If needed, repeat steps to deploy additional micrografts.

Note the delivery systems and occluding devices (micrografts) disclosedherein have been described for use for treating intracranial aneurysms.It should be appreciated that the delivery systems and occluding devices(micrografts) can also be utilized for treating aneurysms in otherregions of the body or for treating other vasculature or for treatingnon-vascular diseases.

Note the delivery systems disclosed herein can be utilized to deliverthe various micrografts disclosed herein and specific micrograftsdiscussed in conjunction with specific delivery systems are provided byway of example.

The above delivery systems and concepts are preferred ways to deliverthe intra-aneurysmal micrograft. The micrograft however mayalternatively be constructed to mate with other microcoil deliverysystems that provide a timed and controlled release, e.g., electrolyticdetachment as described in U.S. Pat. No. 5,354,295 and its parent, U.S.Pat. No. 5,122,136, both to Guglielmi et al., interlocking ball and keyway as described in U.S. Pat. No. 5,261,916 to Engelson, and pusher withmating ball configuration as described in U.S. Pat. No. 5,304,195 toTwyford et al.

In some applications, other vaso-occlusive devices such as platinummicrocoils may be used in combination with the micrografts of thepresent invention to occlude the aneurysm.

While the above description contains many specifics, those specificsshould not be construed as limitations on the scope of the disclosure,but merely as exemplifications of preferred embodiments thereof. Thoseskilled in the art will envision many other possible variations that arewithin the scope and spirit of the disclosure as defined by the claimsappended hereto.

What is claimed is:
 1. A vascular graft configured for occluding avasculature of a patient, the vascular graft comprising: an absorbentbiocompatible textile structure forming a tubular structure, the textilestructure formed of multifilaments forming absorbent walls ofmultilayered filaments such that a first plurality of filaments forms anouter layer overlying a second plurality of filaments forming an innerlayer spaced radially inwardly from the outer layer, the outer and innerlayers extend along a length of the metal coil and have spaces in theinner and outer lavers for blood entry; and a core element having aproximal end, a distal end and a lumen within the core element, the coreelement positioned inside the biocompatible structure and attached tothe biocompatible structure, the core element formed of a metal coilhaving a proximal end and a distal end; wherein the textile structurehas a proximal opening at a proximal end and a distal opening at adistal end for blood flow into the distal end, and the vascular graftforms a capillary tube with the absorbent walls, the capillary tubecreating a capillary effect within the vascular graft when thebiocompatible structure is exposed to blood such that blood istransported in a proximal direction through the distal opening in thevascular graft and through the vascular graft wherein blood clots, andblood absorbed by the graft is trapped within the textile structure. 2.The vascular graft of claim 1, wherein the tubular structure isnon-self-expanding along its length.
 3. The vascular graft of claim 1,wherein the core element has multiple coils and the vascular graftfurther comprises a tube secured to and positioned within the coils ofthe coiled structure, wherein a distal portion of the tube is within thetextile structure, the tube having a lumen extending therethrough from adistal opening to a proximal opening to enable blood flow into and outof the tube.
 4. The vascular graft of claim 3, wherein a proximal end ofthe tube extends proximally of the coiled structure and the textilestructure is attached over an outer surface of the tube.
 5. The vasculargraft of claim 3, wherein the tube is twisted or screwed into severalcoils of the core element to extend between the coils, and the tubereceives a delivery member.
 6. The vascular graft of claim 3, whereinthe lumen of the tube is dimensioned to receive a delivery member andthe distal opening of the lumen is distal of the proximalmost coilwinding of the core element.
 7. The vascular graft of claim 6, whereinthe tube is twisted into the coils of the core element and is flush withan outer diameter of the core element.
 8. The vascular graft of claim 1,wherein the biocompatible structure has an outer diameter less than0.027 inches.
 9. The vascular graft of claim 1, wherein thebiocompatible textile structure includes a braid formed of a pluralityof wettable yarns formed by the filaments, the yarns spaced to wickblood when placed in contact with blood creating a second capillaryeffect, the yarns interlaced to form a fluid barrier that maintainspermeability.
 10. The vascular graft of claim 9, wherein the filamentsare spaced to wick blood when placed in contact with blood creating athird capillary effect to promote blood clotting.
 11. The vascular graftof claim 10, wherein a drug is added to an inner diameter of the tubularstructure, the drug infused into a wall of one or more fibers.
 12. Thevascular graft of claim 1, wherein the vascular graft further comprisesa separate radiopaque marker band, a portion of the radiopaque markerband positioned within the tubular structure and attached to the coreelement and secured to the tubular structure by melting the tubularstructure over the marker band.
 13. The vascular graft of claim 1,wherein the vascular graft is movable to a substantially linearconfiguration for delivery and returns to a non-linear configuration forplacement within the vasculature.
 14. The vascular graft of claim 1,wherein the core element is made of a radiopaque material and wound intoan open pitch helical coil.
 15. The vascular graft of claim 1, whereinthe vascular graft is shaped in a pre-biased secondary helical shape.16. A vascular graft configured for occluding a vasculature of apatient, the vascular graft comprising: an absorbent biocompatibletextile structure forming a tubular structure; and a core element havinga proximal end, a distal end and a lumen within the core element, thecore element positioned inside the biocompatible structure and attachedto the biocompatible structure, wherein the textile structure has aproximal opening at a proximal end and a distal opening at a distal endfor blood flow into the distal end, and the vascular graft forms acapillary tube creating a capillary effect within the vascular graftwhen the biocompatible structure is exposed to blood such that blood istransported in a proximal direction through the distal opening in thevascular graft and through the vascular graft wherein blood clots,wherein the textile structure comprises a plurality of yarns formed by aplurality of polymer filaments, the plurality of filaments having afirst set of pores therebetween for absorption of blood, the pluralityof yarns having a second set of pores therebetween for absorption ofblood to create a second capillary effect, the first set of poresbetween the filaments configured for absorption of blood creating athird capillary effect.
 17. The vascular graft of claim 16, wherein thetubular structure forms a braid forming a continuous circumferentialwall along a length.